Method and device for operating an internal combustion engine

Abstract

A method and a device for operating an internal combustion engine make it possible to set a setpoint value for the overall fresh air mass flow as the top control target. The internal combustion engine has a multi-flow air system including a multi-channel air supply and a corresponding multi-channel exhaust gas discharge, exhaust gas being recirculated from the multi-channel exhaust gas discharge into the multi-channel air supply and the exhaust gas recirculation being regulated for setting a setpoint fresh air mass flow. A value for the required overall fresh air mass flow of the internal combustion engine is predefined for at least one exhaust gas recirculation channel as the setpoint for the exhaust gas regulation.

Description

BACKGROUND INFORMATION[0001]It is known that large diesel engines in particular are increasingly equipped with dual-flow air systems. Two turbochargers compress the two fresh air mass flows into one combined boost pressure. The exhaust gas mass flows drive the turbines of both turbochargers. An appropriate multi-channel air supply and an appropriate multi-channel exhaust gas discharge are provided in such a dual-flow or multi-flow air system. The exhaust gas is recirculated from the multi-channel exhaust gas discharge into the multi-channel air supply, and the exhaust gas recirculation is regulated for setting a setpoint fresh air mass flow.[0002]Standard methods enable either a) the adjustment of the fresh air mass flow required for meeting the emission standard by activating the exhaust gas recirculation valves in the exhaust gas recirculation channels in an identical way or b) the adjustment of the individual air paths or air channels to the same overall proportion of the fresh a...

AI Technical Summary

Benefits of technology

[0003]The method according to the present invention and the device according to the present invention for operating an internal combustion engine have the advantage over the related art that a value for the required total fresh air mass flow of the internal combustion engine is predefined as the setpoint value for the exhaust gas recirculation regulation for at least one exhaust gas recirculation channel. It is ensured in this way that a setpoint value for the total fresh air mass flow is achieved, thereby meeting the emission standards even in the presence of unequal air paths or air channels, or unequal exhaust gas recirculation valves, e.g., due to manufacturing tolerances or aging. Within this scope, optimum air mass equalization is aimed at in a manner known to those skilled in the art, in order to limit the agility loss.

[0005]It is a further advantage when the value for the required overall fresh air mass flow of the internal combustion engine is predefined as the setpoint value for the exhaust gas recirculation regulation for the at least one exhaust gas recirculation channel in the event when an error is detected at an actuator or at a sensor in one of the control loops for the exhaust gas recirculation regulation. In this way, the standard method mentioned above under b) may initially also be used. Only when an error is detected at an actuator, an exhaust gas recirculation valve for example, or at a sensor, an air mass flow rate sensor for example, in one of the control loops for the exhaust gas recirculation regulation, is the achievement of a setpoint value for the overall fresh air mass flow impressed on the controller of at least one air path as the new control target for the exhaust gas recirculation regulation of the assigned exhaust gas recirculation channel.

Problems solved by technology

In case a), this results in unequal air mass flows in the individual air paths or air channels, which results in very low turbocharger rotational speeds.

This in turn results in very poor startup behavior or in low agility.

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